WANT A MODERN TURBO 6? FORGET BARRAS, 2JZS, ATLAS-6S, OR RBS
It is an uncomfortable fact for some of us older chaps that, while we think of turbo DOHC 6-cylinder engines like the Nissan RB, Toyota JZ and Ford Barra as being a lovely modern way of making power, they're actually old tech now. A port-EFI DOHC in-line six with turbocharger power redefined how much power could reliably be made from small-capacity engines in the early 2000s, and they still run hard today... but technology has moved on.
The Nissan RB is over 40 years old. When Nissan introduced it to the world way back in 1985 the Chevy small-block was only 30 years old, so just marinate on that one for a while. Toyota's JZ-series entered production just five years later in 1990, and even the mighty 4.0-litre Ford Barra is almost 25-years-old, having been unleashed on the Aussie public back in 2002.
THE PROBLEM WITH RBs, JZs & BARRAs
Cast iron blocks have great strength, to a point, but they're heavy and this affects the handling of your street car. Additionally, time has marched on and stocks of these engines have only been going down as power-thirsty modders have blown up countless examples in the chase for tar-burning horsepower.
So (unlike 2005) you can't get a sub-20,000km-old 2JZ for $1500, jam 30psi into it and expect it to live without needing a timing belt, valve stem seals and possibly a lot more work. As I said above, they're old engines and they're starting to get expensive as they're harder to find today: the Barra ended production 10 years ago (2016), the RB stopped in 2004, and the 2JZ in 2007.
SO, WHAT NOW?
In the face of ever-tightening emissions standards and mass market who seemingly don't want performance internal combustion cars anymore, many enthusiasts thought the days of glorious turbo six-cylinder performance were over. However, there is a rudely good engine available in a wide range of contemporary cars - most being rear-drive, too - which loves to be boosted up to make huge power.
Salvation for force-fed six fiends comes from Germany, and an unlikely source: BMW. Formerly renowned for their naturally aspirated in-line six-cylinder engines, BMW has been building turbo variants as far back as 2006, with the N54 showcasing a pair of snails on a three-litre DOHC six, before it was replacing by the single-turbo N55, and now the subject of today's post: the B58.
If you've watched the last couple of episodes of MCM (EPISODE 1, or EPISODE 2, or EPISODE 3) you'll have seen MOOG's B58-powered M140i in action.
GIVE US THE SKINNY, WORKSHOP MANUEL
Introduced in the 2015 F30 340i 3 Series, the B58 is a wholesale new engine over the previous N-series turbo sixes. It displaces 2998cc, and runs 11:1 compression ratio, with a strong, closed-deck aluminium block increasing the engine's weight 8kg over the N55 for a total dry weight of 139kg.
It is a long-stroke design with an 84mm bore and 96mm stroke, with a four-valves per-cylinder DOHC aluminium cylinder head featuring direct-injection fuelling, dual-VANOS variable valve-timing and BMW Valvetronic variable valve-lift technology.
The turbo is a single twin-scroll unit using water-to-air intercooling; they run a traditional wet sump with a sensor instead of a dipstick and a water heat exchanger; and these engines are factory rated between 213kW and 324kW (290hp-440hp) with a spicier S58 available.
PUT SOME HEAT IN THE CHICKEN, MATE - GIVE US THE SPICE!
The S58 is still an all-aluminium three-litre DOHC six, but it uses a lower compression ratio (9.3:1). There are also twin-turbochargers, and it produces between 338-375kW (460hp-560hp).
These are used in BMW M-Sport and Alpina cars as dedicated high-performance variants. Now, anyone who has been keeping up to date with what late-model cars are being made into ridiculously fast underpants-ruiners will have heard of the G-series M2, M3 and M4, and know these things are being turned into luxury dailies capable of single-digit quarter-mile times with ridiculously little work.
So, the B58 and S58 are certainly tasty schnitzel, Ja?
B58 IS BLOODY GREAT, MATE
The original 2015-spec B58 was replaced in 2019 by the updated B58TU that features a few upgrades which make bolting on upgrades to make over 400rwhp (+300rwkW) a snack, while there are plenty of people pushing them to more than double that amount with internal work.
The TU-spec engine features a simpler single-piece timing chain to make the front-end of the engine more compact, as this is the spec which is used in Toyota's Mk5 Supra, and it also has a better (bolt on) fuel pump that runs higher pressure. For people with Gen1 B58s, you can fit this to your engine to make increasing the power easier - a handy little fact.
So we've got a light, strong three-litre six. What's the catch?
EASE UP, CHACHI. THEY'RE NOT PERFECT.
All engines have problems, and the B58 is no exception. Direct-injection engines don't mist fuel onto the backs of intake valves like a port-injection engine, so carbon build-up in the head and through the crankcase ventilation system (PCV) is a common issue among DI engines of all sorts, and the B58 is no exception to this.
Similarly, turbocharged, DI engines with high compression ratios generate a LOT of heat. This places huge strain on the cooling system which, in the B58, is complex - BMW split the cooling for the head and the block between two circuits and that means there are a LOT of hoses and they're not you're simple old style slip-on rubber you find in any regular parts store.
These are specially moulded with proprietary clips to fit specific sections of the engine. Similarly, the plastic oil filter housing can leak, and the mechanical high-pressure fuel pumps often wear. Some owners find high-kilometre B58s can wear out coilpacks leading to spark issues.
However, all in all, these engines are a tough modern powerplant.
SHOULD I SELL MY SPLEEN AND GET ONE?
Strewth, Pookie, I dunno mate. How attached to your spleen are you?
In all seriousness the B58 was fitted to over 40 different BMW models since it hit the scene over 10 years ago, and there is a huge amount of knowledge on these engines today thanks to the high-performance scene jumping in boots and all to support them.
If you're after a modern, safe, comfortable car you can make ridiculously fast, I think you could do a lot worse than looking at a B58-powered BMW. Just find a good independent mechanic; service it on the dot; and never skimp on maintenance.
